<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>背景色半透明</title>
    <style>
        body{ background: #fff url(wzry.webp) no-repeat fixed top;
        }
        div{
            width: 100%;
            height: 200px;
            background: rgba(0, 0 ,0 ,.3);
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>